Traffic monitoring system

ABSTRACT

A pair of start and stop sensors are positioned in each lane of a multi-lane road a known distance apart and are actuable by passing cars. Individual time delay means are associated with each lane and are energized each time the start sensor of the associated lane is energized. A computing means has a cycling state and a non-cycling state, and can be energized into its cycling state only under certain conditions, e.g., by the actuation of a start sensor at a time when the associated time delay means is de-energized. Also, under these conditions, a lockout logic means functions to energize the remaining time delay means for the cycle duration, thereby preventing said certain conditions from occurring in any other lane until the computing cycle is completed. During energization of any time delay means the subsequent actuation of the associated start sensor cannot energize the computing means. However, such subsequent actuation will re-energize the associated time delay means. Therefore, since a vehicle&#39;&#39;s front wheels pass over the start sensor before the rear wheels do, the computation cycle cannot be initiated by the rear wheels, which cycle would result in an incorrect speed computation. Other logic means cause a camera to optically track the monitored vehicle in accordance with its speed and lane, and take a picture thereof if the speed lies in predetermined ranges. Still other logic means disable the system in the event of a very slow moving vehicle, which might occur due to an accident or heavy traffic.

e i United States Patent [1 1 3,689,878

Thieroff A Sept. 5, 1972 [54] TRAFFIC MONITORING SYSTEM means areassociated with each lane and are energized [72] Inventor. Keith LThie'mfl Grand Prairie each time the start sensor of the associated laneis Tex energized. A computing means has a cycling state and g anon-cycling state, and can be energized into its [73] Assignee: LTVAerospace Corporation, Dalcycling state only under certain conditions,e.g., by the y las, Tex. actuation of a start sensor at a time when theassociated time delay means is de-energized. Also, under [22] Flled'June 1970 these conditions, a lockout logic means functions to [21]App]. No.: 49,086 energize the remaining time delay means for the cycleduration, thereby preventing said certain conditions from occurring inany other lane until the computing [52] U.S. Cl. ..340/31 R cycle iscompleted Dun-Hg energization of any time [51] Ilfl. Cl. ..G08g 1/10delay means the Subsequent actuation of the [58] Field of Search 340/22, 31, 32, 33, 34 sociated Stan sensor cannot energize the computingmeans. However, such subsequent actuation will re- [56] References Citedenergize the associated time delay means. Therefore, NTS since avehicles front wheels pass over the start sensor FOREIGN PATE QAPPLICATIONS before the rear wheels do, the computation cycle can-975,532 11/1964 Great Britain....; ..340/31 not be initiated by the rearwheels, which cycle would Primary Examiner-William C. CooperAtt0meyDonald W. Phillion and H. C. Goldwire [57] ABSTRACT A pair ofstart and stop sensors are positioned in each lane of a multi-lane roada known distance apart and are actuable by passing cars. Individual timedelay ROAD CENTER LINE\ result in an incorrect speed computation. Otherlogic means cause a camera to optically track the mom tored vehicle inaccordance with its speed and lane, and take a picture thereof if thespeed lies in predetermined ranges. Still other logic means disable thesystem in the event of a very slow moving vehicle, which might occur dueto an accident or heavy traffic.

29 Claims, 17 Drawing Figures TIME DELAY PULSE TRAFFIC LANE "A" SHOULDER45 1 "l GENERATING MEANS J 28 1 CAMERA 233 SECOND 1 fillll IRErmesERAsLE To e i k ONE SHOT M.V. N29 3 3 S ,3? ,0 l 43 I 55 f ll 62SPEED COMPUTING 42 l i MEANS I Y J I 32 5 39 1 I "Ill PICTURE TAKING 156% o 49 DECISION MEANS 1 TIME DELAY PULSE 2. I AND SHAPING MEANS CAMERAWRROR TRACKING MEANS I PATENTEDSEP 5l972 saw our 15 5 l A E /v N QE o203 N 205 ...l\ 225 3 5a NI 26m wmm KEITH L. THIEROFF INVENTOR BYATTORNEY A NVN PZDOQ x42 wmOv PATENTEDSEP 5 I972 sum 110815 0200mm mmd8m Qmm KEITH L. THIEROFF INVENTOR QM/0%;

ATTORNEY SHEET 12UF15 Oh humJwm wzdj KEITH L. THIEROFF INVENTOR QMA %VATTORNEY PATENTEDSEP 51912 SHEET l'40F15 mOmmzi 304m 0Em mh m0 ZOCbmEQmmv TRAFFIC MONITORING SYSTEM This invention relates generally totraffic control systems and more particularly to a traffic controlsystem employing a pair of sensors positioned across the roadway in thepath of the traffic being monitored.

In the prior art there are many types of speed detecting devices whichemploy road sensors to obtain the necessary data for determiningvelocity. The basic concept involved is as follows. A pair of sensors,including a start sensor and a stop sensor, are positioned on theroadway a' known distance apart, each sensor being responsive to a caror other vehicle passing thereby. Means are provided to measure the timeinterval required for the car to pass between the start sensor and thestop sensor. Since both time and distance are now known it is possibleto either compute velocity directly, or to refer to a table which givesvelocity in terms of the elapsed time.

Since the speeds computed by these devices are often utilized as thebasis for issuing speed violation tickets it is essential that theyproduce accurate measurements of speed. One requirement for producingsuch accurate measurements is that both the start and the stop sensorsmust be actuated by the same pair of wheels on a given vehicle. It isreadily apparent that if the rear wheels of a vehicle activated thestart sensor and the front wheels of the same vehicle activated the stopsensor, a lesser time would have elapsed than if the front wheelsactivated both the start and the stop sensors. Consequently, thevelocity of the car would have been calculated to be higher than itactually was.

In most prior art systems a given car will activate the start sensor orswitch as it passes thereby, and thus initiate the speed computationcycle. A short time later the car will pass the stop switch and therebyestablish the time interval required to traverse the distance betweenthe start and stop switches. The velocity computation can then becompleted and the cycle of operation terminated, usually with aphotograph of the vehicle being made in the event that a speed violationhas occurred. In most of these prior art devices reactivation of thestart switch by subsequently arriving vehicles will produce no effectupon the computation of the velocity of the first vehicle to activatethe start switch. 'On the other hand, however, in most prior art devicesit is possible for the cycle to become completed at a time when the rearand front wheels of the subsequent car are straddling the start switch.Under such conditions the start switch will be activated by the rearwheels of the subsequent vehicle. Thus when the front wheels of saidsubsequent vehicle pass the stop switch an incorrect measurement of theelapsed time will have occurred and an incorrect computation of velocitywill result.

The problem is particularly prevalent in prior art devices which monitora plurality of traffic lanes. In such devices separate start and stopsensors are placed in each lane, with each pair of sensors supplyinginput start and stop signals to a common computation device. Except inthe case of very slow moving traffic, means are provided in some ofthese prior art devices to prevent a subsequent car in a given lane tobe straddling the start switch at the termination of a cycle caused by apreceeding car in the same lane. However, no known systems havestructure which will prevent cars in the other lanes from being in astraddling position over their start switches at the termination of saidcycle, and thereby initiating a false speed computation.

Another problem appearing in prior art devices is the obtaining of aclear, unblurred picture of an offending vehicle. In the case ofmulti-lane traffic monitoring, this last-mentioned problem involves twoseparate considerations. The first consideration is the problem ofobtaining sufficient detail in the photograph. In prior art multi-lanedevices the camera is usually positioned so that it takes a photographof all the lanes being monitored each time a violation occurs in any oneof the lanes. It is apparent that the picture detail will beconsiderably less than that which would be obtained if the field of viewof the camera contained substantially only the speeding vehicle.

The second consideration involves the blurring of the picture producedby the motion of the vehicle with respect to the camera.

Most prior art devices attempt to overcome the problem of blurringeither by using a. very fast film or by placing the camera either farenough in front of the car or far enough in back of the vehicle beingphotographed so that the component of velocity normal to the line ofsight of the camera is small.

With todays high speed traffic flow, however, the usage of fast filmsdoes not produce satisfactory results. Nor has the placing of the camerasubstantial distances from the car being photographed produced goodresults. The latter expedient has the disadvantages of lessened picturedetail due to the distance between camera and car and also has anincreased risk of other traffic intervening between the camera and thecar being photographed.

An additional problem inherent in known prior art system arises in thecase of very slow moving traffic, or stop and start type traffic, whichsometimes in cases of accidents or congested traffic. Under suchconditions it is possible for a car to have its front and rear wheelsstraddle the start sensor for several seconds or more, during which timeall of the time delays in the system will expire and the system will bein condition for a new cycle. Thus, when the straddling car movesforward, its rear wheels will actuate the start sensor and subsequentlythe front wheels will actuate the stop sensor, thereby producing anerroneously high speed computation.

It is a primary object of the invention to provide a speed detectingdevice wherein false cycling operations cannot occur, either in thesingle lane or in the multilane forms of the invention.

A second purpose of the invention is to provide a speed detecting devicein which a clear, unblurred picture is taken both of the offendingvehicle and its driver.

A third purpose of the invention is to provide a multilane speeddetecting device in which a single camera can be focused in any lanecontaining a violating vehicle and further in which false operation ofthe device is not possible.

A fourth object of the invention is a multi-lane speed detecting devicein which means are provided to enable the field of view of the camera tooptically track the speeding vehicle, taking into account the speed ofthe vehicle, and thereby obtaining clear, unblurred picvehicle s motion.

A fifth aim of the invention is a multi-lane speed detecting deviceincluding means for enabling the field of view of the camera tooptically track the speeding vehicle, taking into account not only thelane in which the car is traveling but also the speed of the car, andthereby obtaining clear pictures of the car and its driver, unblurred bythe motion of the vehicle and well centered in the field of view of thecamera.

A sixth purpose of the invention is a multi-lane speed detecting devicein which the lane and the velocity of the vehicle are first determinedand in which the field of view of camera is then caused to opticallytrack the vehicle in accordance with the determined lane and thevelocity to enable the taking of a clear, unblurred pic ture of thevehicle and its driver.

A seventh purpose of the invention is a multi-lane speed detectingdevice in which the lane and-speed of the vehicle are determined first,and in which a camera assembly is thereby caused to be aimed tooptically frame said vehicle in its field of view, thus permitting amore detailed photograph to be made of the vehicle as compared to anarrangement whereby all lanes are framed in the cameras field of vieweach time a picture is taken.

An eighth purpose of the invention is the improvement of speed detectormeans generally.

In accordance with the invention there are provided start and stopsensor means positioned a distance d apart in the path of the trafficflow and constructed to generate start and stop pulses, respectively, asthey are actuated by a passing vehicle.

The speed detecting device has a cycling state and a non-cycling state.The cycling state is initiated when a pair of wheels passes the startsensor, but only if the device is in a non-cycling state at such time.Once the cycling state is initiated a computing means measures the timeinterval t between actuation of the start and stop sensors and thencomputes the velocity of the passing vehicle.

Tracking means are responsive to the computed velocity to enable thefield of view of the camera to optically track the passing vehicle andto photograph the vehicle if the velocity thereof lies withinpredetermined ranges.

Also provided is a time delay pulse generator which is energized toproduce a time delay pulse each time the start sensor is energized,whether the device is in its cycling state or in its non-cycling state.However, only if the device is in its non-cycling state at the time saidstart sensor is actuated will the cycling state he initiated.

Thereafter, during the presence of a time delay pulse, furtherinitiation of the cycling state will be prevented by the presence ofsuch time delay pulse. Thus, since the time delay pulse generating meansis reenergized by each actuation of the start sensor, the possibility ofa subsequent vehicle having its front and rear wheels straddle the startsensor at the termination of the cycling state is virtually eliminated,except in those cases where a car is traveling at a very low speed of afew miles per hour. To overcome the last-mentioned possibility, logic isprovided to cause continuous and uninterrupted energization of said timedelay pulse generating means until after said stop sensor is energized.

More specifically such logic means are provided which measures the timeinterval between successive actuations of said start sensor. If saidmeasured time intervals should exceed a given maximum before the stopswitch is actuated then a signal will be generated by said logic meanswhich will disable the device and prevent the taking of a picture untilthe stop sensor is actuated and a new, subsequent cycle of operation isinitiated.

In the multi-lane form of the invention separate start and stop sensorsare positioned in each lane of traffic, with the output start and stoppulses of each pair of sensors being supplied to common computing andphotographing means, but to individual time delay pulse generatingmeans. The outputs of each of said individual time delay pulsegenerating means are also supplied to the common computing andphotographing means.

Lockout logic, which is provided in the multi-lane form of theinvention, responds to the initiation of the cycling state of the deviceby actuation of the start sensor in any given lane to prevent subsequentenergization of the computation means by actuation of the start sensorin. any other lane during the initiated cycling operation. Said lockoutmeans, however, does not prevent the reenergization of the time delaypulse generating means in any of said lanes during said cyclingoperation, including said given lane.

Consequently, such lockout means in no way prevents the time delay pulsegenerating means in said other lanes from performing their normalfunction of preventing a car from straddling the start sensor in one ofsaid other lanes at the termination of an operating cycle.

As indicated briefly above the time delay is of sufficient length toensure that a car traveling above a minimum rate of speed will have itsrear wheels pass over the start sensor before the expiration of saidtime delay pulse.

As in the case of the single lane mode, logic is provided to preventfalse operation in those instances where cars are traveling at anextremely low rate of speed, such as might occur for example in veryheavy rush hour traffic, when it is possible that said time delay pulsemight terminate after the front wheels of the vehicle have passed overthe start sensor but the rear wheels have not,

Also provided in the multi-lane form of the invention are logic meanswhich respond to the initiation of a cycle of operation to energize aservo motor which then functions to aim the camera at the lane in whichthe car is traveling which initiated said cycle.

Further logic means are provided to then produce a voltage whosemagnitude is determined not only by the velocity of the car but also bythe lane the car occupies, to cause said camera to optically track thecar after the occurrence of a speed violation has been determined.

It is to be noted that in the preferred embodiment of the invention thecamera itself is not driven by the servo motor. Rather a mirror, whichhas much less mass than the camera, is driven by the servo motor tooptically track the vehicle and reflect the image thereof into thecamera lens.

The above-mentioned and other objects and features of the invention willbe more fully understood from the following detailed description thereofwhen read in conjunction with the drawings in which:

FIG. 1 is a general logic diagram of a single lane mode of theinvention;

FIG. 2 is a logic diagram of the logic for computing the speed of amonitored vehicle;

FIG. 3 is a diagram of the logic for determining whether the computedspeed constitutes a violation and consequently whether a picture shouldbe taken of the vehicle, and also includes logic means for providing atime delay to permit such picture taking;

FIG. 4 is a more detailed logic diagram of the strucl5 FIG. 6 is adiagram of the logic for preventing activa- 20 tion of the camera whenthe speed of the vehicle is below a predetermined minimum value;

FIG. 6a is an alternative means for preventing camera actuation when thespeed is below a predetermined value;

' FIGS. 7 and 8 show the logic diagram for a multi-lane mode of theinvention;

FIG. 8a shows the multi-lane logic diagram for preventing activation ofthe camera when the speed of a car is below a predetermined value;

FIG. 9 shows how FIGS. 7 and 8 fit together;

FIGS. 10 and 11 show a more detailed logic diagram of the structure ofFIGS. 7 and 8 and in particular show a more detailed level of the logicemployed in the NOR gate type flip-flop circuits ofFIG. 8;

FIG. 12 shows how FIGS. 10 and 11 fit together;

FIG. 13 is a diagram of the logic employed in the multi-lane mode forenabling the camera to optically track a violating vehicle in anapproximate manner in accordance with its computed speed and inaccordance with the lane in which it is traveling;

FIG. 14 is another diagram for optically tracking the speeding vehiclein accordance with computed speed and the lane in which it is traveling,but in a more precise manner than that shown in FIG. 13; and

FIG. 15 is a chart showing the physical representations of themathematical terms employed in FIG. 14.

The specification will be organized in accordance with the followingoutline.

I. GENERAL DESCRIPTION OF SINGLE LANE MODE A. General System (FIG. 1)

B. Speed Computing Logic (FIG. 2)

C. Picture Taking Decision Logic (FIGS. 3 and 4) D. Camera TrackingMeans (FIG. 4)

E. Slow Moving Car Detecting Logic (FIG. 6)

II. OPERATION OF SINGLE LANE MODE A. General System Operation (FIG. 1)

B. Speed Computing Logic (FIG. 2)

C. Picture Taking Decision Logic (FIGS. 3 and 4) D. Camera TrackingMeans (FIG. 5)

E. Slow Car Detecting Means (FIG. 6 and 60) III. GENERAL DISCUSSION OFMULTI-LANE MODE A. General System (FIGS. 7 and 8) l. NOR Gate LogicFlip-Flop (FIGS. 10 and I1) B. Multi-Lane Logic for Approximate Tracking(FIG. 13)

C. Multi-Lane Logic for Precise Tracking (FIGS. 14

and 15) IV. OPERATION OF MULTI-LANE MODE A. General System (FIGS. 7, 8and 8a) 1. NOR Gate Logic Flip-flop (FIGS. 10 and 11) B. Multi-LaneLogic for Approximate Tracking (FIG. 13)

C. Multi-Lane Logic for Precise Tracking (FIGS. 14

and 15) It can be seen from the foregoing outline that a generaldescription of the single lane mode of the invention will be set forthfirst, followed by a discussion of the operation of such single lanemode.

Subsequently the multi-lane mode will be discussed generally, followedby a discussion of the operation thereof.

I. GENERAL DESCRIPTION OF SINGLE LANE MODE A. General System (FIG. 1)

Referring now to the single lane mode of the invention shown in FIG. 1 acar 22 is shown in a position wherein both its front and rear wheelshave passed over the start sensor 20 and only the front wheels havepassed over the stop sensor 21.

Each time a pair of wheels passes over either the start sensor 20 or thestop sensor 21 a pulse is generated in the sensor. More specifically apulse, such as pulse 23, is generated each time a pair ofwheels passesover start sensor 20, and a pulse 24 is generated each time a pair ofwheels passes over stop sensor 21.

It is to be noted that throughout the specification, pulses will bedesignated as having an upper or lower level, with the upper levelrepresenting a binary one condition and the lower level representing abinary zero condition.

As will be seen later the logic is so designed that only the pulsesgenerated by the passage of the front wheels over the start and stopsensors are utilized in computing the speed of the vehicle. The pulsesgenerated by the rear wheels are ignored by the logic of the system.

In order to compute velocity, the time t required for the front wheelsof a vehicle to pass between the start sensor 20 and the stop sensor 21is measured. Since the distance d between the sensors 20 and 21 isknown, the velocity can be obtained by dividing said distance d by themeasured time t.

The start and stop pulses 23 and 24 are supplied to the logic within thedotted block 60 which has two outputs 61 and 62 leading to the reset andthe set inputs respectively of flip-flop 32. I

The primary function of the logic within dotted block 60 is to ensurethat only those start and stop pulses generated by the front wheels ofthe vehicle are employed in determining the velocity of the vehicle. Thefunction of each of the logic elements within the block 60 will be morefully understood from the detailed discussion of the operation of thecircuit which will be set forth later herein under sections II A and IIB.

The flip-flop circuit 32 is reset by the start pulse 23, through NORgate 30, and set by the stop pulse 24, so that the output signals on itstwo output leads 36 and 37 constitute a measure of the time intervalthat the front wheels of the car 22 are in the speed zone between thestart and stop sensors. Such time interval is indicated generally bywaveform 51, which represents the output of terminal 36 of flip-flop 32,and can be seen to begin at time t, and terminate at time 1 A speedcomputing means 38 functions to produce an output signal which isdirectly representative of the speed of the vehicle. In the particularembodiment of the invention shown and described in this specificationthe speed computing means 38 is digital in nature and supplies a burstof output pulses immediately following and proportional to the timeinterval t t of wavefonn 51. The number of such pulses in said burst isa direct representation of the speed of the vehicle.

Should the speed of the vehicle constitute a speed violation, a picturetaking decision means 39 is energized which produces a signal on itsoutput terminal 41.

Such output signal on terminal 41 performs two functions. Firstly, acamera operating solenoid 43 is responsive thereto to cause theoperation of camera 44. Secondly, such signal is supplied to cameramirror tracking means 40 which is constructed to also respond to thecomputed velocity of the vehicle via lead 49 to cause the mirror 45 tooptically track the vehicle. A mechanical linkage 52 is supplied betweenthe camera mirror tracking means 40 and the mirror 45 to enable suchtracking.

More specifically, once it has been determined that the speed of thevehicle 22 is a violation, the mirror 45 is caused to pivot about itaxis 68 to project the image of the car 22 into the field of view ofcamera 44. The rate of pivoting of the mirror 45 is determined by thespeed of the vehicle.

It is to be noted that the mirror 45 is employed for the opticaltracking function rather than pivoting the camera 44 since the mass ofthe mirror 45 is much less than that of the camera 44. Such differencein mass between mirror 45 and camera 44 is important for at least tworeasons. Firstly, the size of the motor required to drive the camera 44would be much greater than that required to drive the much lightermirror 45. Secondly, the rate of angular acceleration of the mirror toits tracking speed must be a very large since the camera is operatedonly a few milliseconds after tracking commences. It is apparent that aconsiderably longer interval time would be required to accelerate theheavier camera 44 to the proper tracking rate.

In the event that the car 22 is not violating a speed regulation it willnot be necessary either for the camera to track the vehicle or to take apicture thereof. In such an event the cycle of operation is completewhen the computation of speed is made.

More specifically the cycle becomes complete at the termination of thepulse generated by pulse generator 26 within logic block 60. Said timedelay pulse in effect determined a minimum cycling time of 2.33 secondswhich is a sufficient time interval for the car to traverse between thestart and stop sensors 20 and 21 and for the computation of thevelocity, and for the determination that no violation has occurred sothat no camera operation is required.

If on the other hand the car is violating a speed law then it isnecessary for the camera to optically track the vehicle and take apicture thereof. After the picture is taken an additional amount of timeis required for a capacitor means to charge in order to be ready toactivate the flash unit in the camera during the next cycle ofoperation.

The pulse generating means 47 functions to provide the additional timeinterval needed in the event a picture is taken. It can be seen that thepulse generating and shaping means 47 is energized by the output signalfrom the picture taking decision means 39 to produce an output signalconsisting of the two pulses 65 and 66, whose leading edges are spaced1.4 seconds apart. Such output pulses 65 and 66 are supplied to timedelay pulse generating means 26 to extend the cycling time of thesystem.

It is to be noted that camera 44 and its associated mirror 68 arelocated well off traffic lane A along which the car 22 is traveling. Infact the camera and the mirror are both located off the shoulder of theroad. Thus, the angle between the line of sight 49 of the camera to thecar 22 and the direction of the car forms an angle 20. Consequently,there will be a component of velocity of the car which is normal to saidline of sight 49. Such normal component of velocity will, unlesscompensated for, cause a blurred picture of the car. It will also beapparent that such normal component of velocity of the car will increaseas the car approaches the camera.

With a sufficiently fast camera and film, and proper lighting, it ispossible to obtain a good picture of the car and the driver shortlyafter the front wheels of the car pass the stop sensor 21, with imagemotion compensation being based solely upon the velocity of the car atthe time the front wheels pass the stop sensor 21. The subsequent,changing normal velocity component of the car with respect to the lineof sight 49 can be ignored.

In other cases, where the picture of the car is taken a greater distancedown the road, Le, a longer time interval of time after the front wheelshave passed stop sensor 21, a more precise tracking means is needed toprovide effective image motion compensation. Such a more precise meansof tracking the automobile is shown in FIGS. 14 and 15 which will bediscussed in more detail later in connection with the multi-lane mode ofthe invention.

I. B. Speed Computing Logic (FIG. 2)

A logic diagram of the speed computing logic is shown in FIG. 2 and iscomprised of a 4.194304 MI-IZ clock pulse source 70 which supplies itsoutput pulses to a 2 divider 71, the output of which is a 2048 HZ pulserate signal.

Upon energization of the start sensor 20 (FIG. 1) NOR gate 73 is openedand a 12 bit time measuring register 72 (FIG. 2) functions to receivethe 2048 I-IZ output from divider 71 and will receive such pulses untilthe stop sensor 21 of FIG. 1 is energized. Thus, the 12 bit timeregister 72 registers a count which is directly proportional to the timethe front wheels of the vehicle are in the speed zone between the startand stop sensors.

A second register 76, designated as the distance register, functions toreceive the 4.19 MHZ signal from clock pulse source 70 after the stoppulse has energized and will continue to receive said 4.19 MHZ signaluntil register 76 becomes full. The output of the last stage of register76, designated as overflow stage 77 is fed back

1. Multi-lane traffic monitoring means for a roadway having a pluralityof traffic lanes, said means comprising: in each of said traffic lanes,a first sensing means and a second sensing means, the second sensingmeans of each lane being spaced a predetermined distance from the firstsensing means of that lane, the first sensing means of each lane beingactuatable by a monitored vehicle passing thereby to generate astart-timIng signal and the second sensing means of each lane beingactuatable by passage thereby of such vehicle to generate a stop-timingsignal; a plurality of delay-signal producing means each connected toreceive each start-timing signal of a respective, corresponding one ofthe first sensing means in a given lane and responsive thereto to emit adelay-inducing signal of a first class, which signal is of apredetermined duration and which begins at a predetermined timesubsequent to reception of the respective start-timing signal by therespective delay-signal producing means; Controlling means responsive tothe concurrence of actuation of the first sensing means in any given oneof said lanes and a nonemitting condition of the corresponding one ofthe delay-signal producing means for providing a computation-initiatingsignal; each of the delay-signal producing means being unaffected by thecomputation-initiating signal when the same has resulted from astart-timing signal from the first sensing means corresponding to thatdelay-signal producing means and each of the delaysignal producing meansbeing responsive to the computationinitiating signal for producing adelay-inducing signal of a second class when the computation-initiatingsignal has resulted from a start-timing signal from a one of the firstsensing means other than the first sensing means corresponding to thatdelay-signal producing means; the controlling means being responsive tothe concurrency of delay-inducing signals of the first class anddelay-inducing signals of the second class to prevent generation of acomputation-initiating signal during the existence of said concurrency;computing means, responsive to the computation-initiating signal and toa subsequent stop-timing signal from actuation of the second sensingmeans of the same lane as that of the first sensing means, the actuationof which has been responded to by the controlling means, for producing afirst output signal v representative of the velocity of the monitoredvehicle; first logic means responsive to the output signal v forproducing a second output signal e if the output signal v lies withinpredetermined values; and recording means responsive to the secondoutput signal e for recording an image of the monitored vehicle. 2.Multi-lane traffic monitoring means in accordance with claim 30comprising: pulse generating means responsive to the output signal e forgenerating a signal having a predetermined duration in time; and inwhich each of said plurality of delay signal producing means isresponsive to said signal generated by said pulse generating means forgenerating a delay-inducing signal of a third class.
 3. Multi-lanetraffic monitoring means in accordance with claim 2 comprising: logiccontrol means for sensing the lane in which the monitored vehicle istraveling and responsive to said output signal v for causing saidrecording means to optically track said monitored vehicle and to beginsaid optical tracking in a sequence wherein the image of said vehicle isrecorded at a predetermined time after the optical tracking begins. 4.Multi-lane traffic monitoring means in accordance with claim 30comprising: logic control means for sensing the lane in which themonitored vehicle is traveling and responsive to said output signal vfor causing said recording means to optically track said monitoredvehicle and to begin said optical tracking in a sequence wherein theimage of said vehicle is recorded at a predetermined time after theoptical tracking begins.
 5. Multi-lane traffic monitoring means inaccordance accordance with claim 1 in which said computing meanscomprises: said logic means for sensing nd responding to the expirationof a time interval of a predetermined length occurring between theinitiation of said computation-initiating signal and actuation of thesecond sensing means in a one of the lanes, actuation of the firstsensing means of which lanE has been responded to by the controllingmeans to provide the computation-initiating signal, for periodicallyenergizing each of said plurality of delay-signal producing means at arate sufficient to maintain each of said plurality of delay-signalproducing means in a continuously energizing state; said second logicmeans being further responsive to actuation of said second sensing meansof said one of the lanes by said monitored vehicle for terminating saidperiodic energization of each of said plurality of delay-signalproducing means.
 6. Multi-lane traffic monitoring means for a roadwayhaving a plurality of traffic lanes, said means comprising: a pair ofsensing means, comprising a first sensing means and a second sensingmeans positioned apart a predetermined distance d in each lane oftraffic, for producing start-timing and stop-timing signals,respectively, in response to actuation by passing vehicles; a pluralityof pulse generating means of a first class, one of each of said pulsegenerating means being responsive to each actuation of a correspondingone of said first sensing means for generating a first delay-inducingsignal having a predetermined duration in time; storage means forstoring a first scalar quantity representative of said predetermineddistance; control circuit means responsive to actuation, by a monitoredvehicle, of the first sensing means of any given pair of said sensingmeans when said pulse generating means of said first class correspondingto said first sensing means is deenergized for producing a computationinitiating signal; time measuring means energizable to measure the timeinterval between said computation initiating signal and the actuation ofthe second sensing means of said given pair of sensing means forproducing a second scalar quantity representative of said time interval;computing means having a computation cycle and responsive to theproduction of said second scalar quantity for dividing said first scalarquantity thereby to produce an output signal v which is representativeof the average velocity of said vehicle during said time interval; eachof said plurality of pulse generating means of said first class, otherthan the pulse generating means of said class energized by actuation ofsaid first sensing means, being responsive to said computationinitiating signal to become energized thereby; means responsive to theoutput signal v, when said signal v lies within predetermined values,for producing an output signal e; and recording means responsive to saidoutput signal e for recording the image of said monitored vehicle. 7.Multi-lane traffic monitoring means in accordance with claim 6comprising: further pulse generating means responsive to the outputsignal e for generating a second delay-inducing signal having apredetermined duration in time; each of said pulse generating means of afirst class being responsive to said second delay-inducing signal forgenerating a third delay-inducing signal.
 8. Multi-lane trafficmonitoring means in accordance with claim 7 comprising: logic controlmeans for sensing the lane in which the monitored vehicle is travelingand responsive to said output signal v for causing said recording meansto optically track said monitored vehicle and to begin said opticaltracking in a sequence wherein the image of said vehicle is recorded ata predetermined time after the optical tracking begins.
 9. Multi-lanetraffic monitoring means in accordance with claim 6 comprising: logiccontrol means for sensing the lane in which the monitored vehicle istraveling and responsive to said output signal v for causing saidrecording means to optically track said monitored vehicle and to beginsaid optical tracking in a sequence wherein the image of said vehicle isrecorded at a predetermined time after the optical tracking begins. 10.Multi-lane traffic monitoring means in accordanCe with claim 6 andfurther comprising: logic means, including said time measuring means,for sensing and responding to the expiration of a time interval of apredetermined length occurring between the initiation of saidcomputation-initiating signal and the actuation of said second sensingmeans in one of the lanes, actuation of the first sensing means of whichlane has been responded to by the controlling means to provide thecomputation-initiating signal, for periodically energizing said pulsegenerating means of a first class at a rate sufficient to maintain saidpulse generating means of said first class in a continuously energizedstate; said logic means being further responsive to actuation of saidsecond sensing means of said one of the lanes by said monitored vehiclefor terminating said periodic energization of said pulse generatingmeans of a first class.
 11. Multi-lane traffic speed monitoring meanscomprising: a pair of sensors comprising a start-timing sensor and astop-timing sensor positioned apart a predetermined distance d in eachlane of traffic, the pair of sensors in each lane constituting means forgenerating start-timing and stop-timing signals, respectively, inresponse to actuation of the sensors by passing vehicles; a separatepulse generating means of a first class connected to each start-timingsensor and energizable in response to each actuation of the connectedstart-timing sensor to generate a delay-inducing signal of a first classhaving a predetermined duration in time; a controlling means responsiveto a given set of conditions consisting of the actuation of thestart-timing sensor by a monitored vehicle in a given lane and theconcurrent non-energization of the pulse generating means of said firstclass connected thereto for producing a cycle initiating signal;computing means having a cycling state and a non-cycling state forcomputing the velocity of the monitored vehicle when in its cyclingstate; said computing means being responsive to said cycle initiatingsignal to enter its cycling state and further responsive to thestop-timing signal generated by said stop-timing sensor in the saidgiven lane to produce an output signal v representative of the velocityof said monitored vehicle; each of the pulse generating means of saidfirst class other than the one of said pulse generating means of saidfirst class connected to the start-timing sensor in said given lanebeing responsive to said cycle initiating signal for emitting adelay-inducing signal of a second class for preventing furtheroccurrence of said given set of conditions during said cycling state;means responsive to the output signal v, when said signal v lies withinpredetermined values, for producing an output signal e; and recordingmeans responsive to said output signal e for recording the image of saidmonitored vehicle.
 12. Multi-lane traffic speed monitoring means inaccordance with claim 11 comprising: pulse generating means of a secondclass and responsive to the signal e for generating a delay-inducingsignal having a predetermined duration in time; each of said pulsegenerating means of the first class being responsive to saiddelay-inducing signal produced by the pulse generating means of thesecond class for generating a delay-inducing signal.
 13. Multi-lanetraffic speed monitoring means in accordance with claim 12 comprising:logic control means for sensing the lane in which the monitored vehicleis traveling and responsive to said output signal v for causing saidrecording means to optically track said monitored vehicle and to beginsaid optical tracking in a sequence wherein the image of said vehicle isrecorded at a predetermined time after the optical tracking begins. 14.Multi-lane traffic monitoring means in accordance with claim 11comprising: logic control means for sensing the lane in which themonitored vehicle is traveling and responsivE to said output signal vfor causing said recording means to optically track said monitoredvehicle and to begin said optical tracking in a sequence wherein theimage of said vehicle is recorded at a predetermined time after theoptical tracking begins.
 15. Multi-lane traffic speed monitoring meansin accordance with claim 11 in which said computing means comprises:logic means for sensing and responding to the expiration of a timeinterval of a predetermined length occurring between the initiation ofsaid cycle initiating signal and the actuation of the stop-timing sensorby the monitored vehicle for periodically energizing said pulsegenerating means of said first class at a rate sufficient to maintainsaid pulse generating means of said first class in a continuouslyenergized state; said logic means being further responsive to actuationof said stop-timing sensor actuated by said monitored vehicle forterminating said periodic energization of said pulse generating means ofsaid first class.
 16. A traffic monitoring means comprising:start-timing and stop-timing sensors positioned in a lane of traffic andspaced apart a predetermined distance for generating start-timing andstop-timing signals, respectively, in response to passing vehicles; afirst pulse generating means responsive to each actuation of saidstart-timing sensor for generating a first delay-inducing signal havinga predetermined duration in time; storage means for storing a firstscalar quantity d representative of said predetermined distance; controlcircuit means responsive to actuation, by a monitored vehicle, of saidstart-timing sensor while said first pulse generating means isde-energized for producing a computation initiating signal; timemeasuring means energized in response to said computation initiatingsignal for measuring the time interval between said computationinitiating signal and actuation of said stop-timing sensor and producinga second scalar quantity representative of said time interval; computingmeans having a computation cycle and responsive to the generation ofsaid second scalar quantity to divide said first scalar quantity dthereby to produce an output signal v which has a value representativeof the average velocity of said monitored vehicle during said timeinterval; means responsive to the output signal v, when said signal vlies within predetermined values, for producing an output signal e;recording means responsive to said output signal e for recording theimage of said monitored vehicle; and tracking means responsive to thesaid output signal v and the value thereof for causing said recordingmeans to optically track said monitored vehicle.
 17. A trafficmonitoring means in accordance with claim 16 and further comprising:further pulse generating means responsive to the output signal e forgenerating a second delay-inducing signal having a predeterminedduration in time, said first pulse generating means being responsive tosaid second delay-inducing signal to generate a third delay-inducingsignal.
 18. A traffic monitoring means in accordance with claim 16 andfurther comprising: logic means for sensing and responding to theexpiration of a time interval of a predetermined length occurringbetween the initiation of said computation initiating signal and theactuation of the stop-timing sensor by the monitored vehicle forperiodically energizing said first pulse generating means at a ratesufficiently high to maintain said first pulse generating means in acontinuously energized state and to inhibit the recording of an image ofsaid monitored vehicle; said logic means being further responsive toactuation of said stop-timing sensor by said monitored vehicle forterminating said periodic energization of said first pulse generatingmeans.
 19. A traffic monitoring means comprising: a pair of start-timingand stop-timing sensors poSitioned in a traffic lane a predetermineddistance d apart and actuated by a vehicle passing thereby to generatestart-timing and stop-timing signals respectively; a delay-signalproducing means connected to receive each start-timing signal andresponsive thereto for emitting a delay-inducing signal which is of afirst class, has a predetermined duration of existence in time, andbegins at a predetermined time subsequent to reception of thestart-timing signal by the delay-signal producing means; control meansresponsive to the concurrence of actuation of said start-timing sensorand to the non-emitting condition of said delay-signal producing meansto provide a computation initiating signal; said control means beingresponsive to said delay-inducing signal of said first class forpreventing generation of an additional computation initiating signal byactuation of said start-timing means during the existence of saiddelay-inducing signal of said first class; computing means responsive tosaid computation initiating signal and to the stop-timing signal fromthe subsequent actuation of said stop-timing sensor to produce a firstoutput signal v representative of the velocity of the monitored vehicle;logic means for producing a second output signal e if said output signalv lies within a predetermined range; recording means responsive to saidsecond output signal e for recording an image of said monitored vehicle;and tracking means responsive to said output signal v for causing saidrecording means to optically track said monitored vehicle.
 20. A trafficmonitoring means in accordance with claim 19 and further comprising:pulse generating means responsive to the output signal e for generatinga delay-inducing signal of a second class and having a predeterminedduration in time, said delay-signal producing means being responsive tosaid delay-inducing signal of the second class for generating adelay-inducing signal of a third class.
 21. A traffic monitoring meansin accordance with claim 19 and comprising: logic means for sensing andresponding to the expiration of a time interval of a predeterminedlength occurring between the initiation of said computation initiationsignal and the subsequent actuation of said stop-timing sensor,actuation of the start-timing sensor of which lane has been responded toby the control means to provide the computation initiation signal, forperiodically energizing said delay-signal producing means at a ratesufficient to maintain said delay-signal producing means in acontinuously emitting state; said logic means being further responsiveto actuation of said stop-timing sensor by said monitored vehicle forterminating said periodic energization of said delay-signal producingmeans.
 22. A traffic monitoring system for vehicles moving in apredetermined path of movement, said system including: detector meansfor detecting vehicles moving in the predetermined path and providing anelectric output which varies in accordance with the speed of movement ofa vehicle moving in the said path; control means operatively associatedwith said detector means responsive to the output of said detector meansfor providing a control output signal when the speed of a vehicle movingin said path exceeds a predetermined value, said control output signalvarying in accordance with the speed of the vehicle; camera meanspositioned adjacent said path for photographing the front end of avehicle moving in said path after said detector means have produced saidoutput after detecting the vehicle, said camera means having a lightsensitive means on which images of the front ends of the vehicles movingin said predetermined path are projectable; tracking means operativelyassociated with said camera means and responsive to said output signalof said control means for tracking the vehicle in accordance with itsspeed and for causing the image of a vehicle Moving in saidpredetermined path whose speed exceeds said predetermined value to beprojected on the light sensitive means of the camera means withoutmovement of said image on said light sensitive means during the periodof operation of said camera means; and means responsive to said controloutput signal for operating said camera means during the period of timesaid tracking means is tracking the movement of a vehicle whose speedexceeds said predetermined value.
 23. The traffic monitoring system ofclaim 22, wherein said tracking means comprises a mirror and means formoving said mirror in accordance with said output signal of said controlmeans for causing the image of the front end of the vehicle whose speedexceeds said predetermined value to be projected to said light sensitivemeans of said camera means.
 24. The traffic monitoring system of claim22, wherein said detector means comprises first and second sensorsspaced apart a predetermined distance and operable successively by eachvehicle moving in said path, the time period between successiveoperations of said first and second sensors varying in accordance withthe speed of the vehicle.
 25. The traffic monitoring system of claim 24,wherein said tracking means comprises a mirror and means for moving saidmirror in accordance with said output signal of said control means forcausing the image of the front end of the vehicle whose speed exceedssaid predetermined value to be projected to said light sensitive meansof said camera means.
 26. A traffic monitoring system for vehiclesmoving a plurality of parallel, predetermined paths of movement, saidsystem including: separate detector means operatively associated witheach of said paths for detecting vehicles moving in said paths and eachproviding an electric output which varies in accordance with the speedof movement of a vehicle moving in its associated path; control meansoperatively associated with said detector means and responsive to theoutputs of said detector means for providing a control output signalwhen the speed of a vehicle moving in any one of the paths exceeds apredetermined value, said control output signal varying in accordancewith the speed of the vehicle; camera means positioned adjacent saidpaths for photographing the driver and the front end of a vehicle movingin any one of said paths after the detector means associated with thepath in which the vehicle is moving has provided an electric outputresponsive to the movement of the vehicle in the path, said camera meanshaving a light sensitive means on which an image of the front end of avehicle traveling in any one of said paths is projectable; trackingmeans operatively associated with said camera means and responsive tothe output signal of said control means for tracking a vehicle inaccordance with its speed and for causing the image of a vehicle movingin one of the paths whose speed exceeds said predetermined value to bemaintained on the light sensitive means of the camera means withoutmovement of said image on said light sensitive means during the periodof operation of said camera means; and means responsive to said controloutput signal for operating said camera means during the period of timein which said tracking means is tracking the movement of a vehicle, inone of said paths, whose speed exceeds said predetermined value.
 27. Thetraffic monitoring system of claim 26, wherein said tracking meanscomprises a mirror and means for moving said mirror in accordance withsaid output signal of said control means for causing the image of thefront end of the vehicle whose speed exceeds said predetermined value tobe projected to said light sensitive means of said camera means.
 28. Thetraffic monitoring system of claim 26, wherein each of said detectormeans comprises first and second sensors spaced apart a predetermineddistance and operable successively by each vehicle moving in theassociated path.
 29. The traffic monitoring System of claim 28, whereinsaid tracking means comprises a mirror and means for moving said mirrorin accordance with said output signal of said control means for causingthe image of the front end of the vehicle whose speed exceeds saidpredetermined value to be projected to said light sensitive means ofsaid camera means.